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Thread: cooked shrimps

  1. #1
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    cooked shrimps

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    found another cooked Malayan shrimp (turned red) at the bottom of my tank a couple of days ago...

    checked with NA, suggested that the temperature could be too high... possibly as i'm using 2x16W compact for a 1.25ft tank... lights are about 1 inch from the water surface then... coz it seems to give more bubbling from the plants...

    Chan says his recommendation is 3 inches from the water surface... would like to hear if you guys follow such a rule...

  2. #2
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    cooked shrimps

    found another cooked Malayan shrimp (turned red) at the bottom of my tank a couple of days ago...

    checked with NA, suggested that the temperature could be too high... possibly as i'm using 2x16W compact for a 1.25ft tank... lights are about 1 inch from the water surface then... coz it seems to give more bubbling from the plants...

    Chan says his recommendation is 3 inches from the water surface... would like to hear if you guys follow such a rule...

  3. #3
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    cooked shrimps

    found another cooked Malayan shrimp (turned red) at the bottom of my tank a couple of days ago...

    checked with NA, suggested that the temperature could be too high... possibly as i'm using 2x16W compact for a 1.25ft tank... lights are about 1 inch from the water surface then... coz it seems to give more bubbling from the plants...

    Chan says his recommendation is 3 inches from the water surface... would like to hear if you guys follow such a rule...

  4. #4
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    cooked shrimps

    found another cooked Malayan shrimp (turned red) at the bottom of my tank a couple of days ago...

    checked with NA, suggested that the temperature could be too high... possibly as i'm using 2x16W compact for a 1.25ft tank... lights are about 1 inch from the water surface then... coz it seems to give more bubbling from the plants...

    Chan says his recommendation is 3 inches from the water surface... would like to hear if you guys follow such a rule...

  5. #5
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    Best if you actually know the temp instead of guessing.

    Can give more info as in filtration, , water chemistry, planted, co2, fert, tankmates etc.

    Quite hard to know what's going on without background info.
    Cheers!!

    Sherwin Choo
    [email protected]

  6. #6
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    will look for a small thermometer tomorrow...
    sorry, no gadgets to test the water chemistry... don't understand them entirely anyway...

    just like to know about the 3 inch rule recommended by Chan...

    thanks

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    don't think there is any rule governing the spacing between light and water surface. when the light is very near the water surface, you will heat up the water. having a bigger gap will reduce the heat transfered to water.

    maybe the 3' recommendation from chan is based on his experience. if you do not wish to increase the gap and having a high temperature problem, you should consider getting a fan.

    you can do a quick check of your tank water temperature by using you hand. if the water feels warm, then the temperature could be >30deg. if it feels cool, then the temperature could be around 28deg.
    thomas liew

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    Not sure if warm water is the cause. But all shrimp when dead turns red. So cud it be other reasons for your dead shrimps?

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    oh i see... that's interesting...
    so i guess its still best to gather the various statistics in order to know more...

  10. #10
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    Maybe you should check your pH and kH first. From there you can check if it's due to co2 poisoning. If you have a NO3 test kist, it would be a plus.

    Also provide us with other info like lighting (amount & duration), co2 (method & duration), tank inhabitants, heavily planted or not, ferterlization, etc.
    Cheers!!

    Sherwin Choo
    [email protected]

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    ammonia posioning?

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    ----------------
    On 11/20/2002 10:46:38 PM

    ammonia posioning?
    ----------------
    It's quite hard to tell what's wrong without information. That's why we should investigate what's wrong with at least some basic info to at least make an educated guess.
    Cheers!!

    Sherwin Choo
    [email protected]

  13. #13
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    ok, here goes:

    Tank Size (WDH in cm) - 39 X 22 X 27
    Volume - 28litres
    Lighting - 2 X 16W Osram Dulux EL Daylight (9 hours daily, just increase from 8 hours yesterday)
    CO2 - Pressurised tank at 1 bubble every 3 seconds or 0.3bps (9 hours daily)
    Filtration - Eheim Liberty 100 (set to minimum, never wash filter)
    Subtrate - Normal gravel from NA with a thin layer of Jaqno Flora Base (40g) in between
    Water Change - 30% to 40% weekly
    Temperature - No thermometer but tank is kept in aircon office
    Fishes - Leopard Cory (2), Otocinclus (2), Platty (1), Siamese Algae Eater (4), Malayan Shrimp (1), Cherry Red Shrimp (11)
    Plants - Mopani wood, Nymphea lotus, Elatine tiandra, Riccia fluitan (floating), not sure about others...


    As for water chemistry, I finally opened my expensive Tetratest kit, did a test after changing water just now. Might not be doing it correctly, but here's what I have:
    pH - 6.8
    KH - 6
    GH - <3
    NO3 - light brown, can assume zero?
    NO2 - light brown, can assume zero?

    My Tank

    any other info required? many thanks!

  14. #14
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    From the results you get, I cannot really say its CO2 overdose but the level is slightly on the high side. 28ppm is to me on the high side but I think Bclee has 30-35ppm for his tank and with no troubles except for introduction of shrimps? Maybe you can try cutting back on CO2 to reach a pH of 7 to see if it helps. Other question, does your office's aircon go "off" after office hrs? If it does, then probably the large temperature swing affects the shrimps faster than the fishes.
    Plant Physiology by Taiz and Zeiger

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    sorry but where do you get this 28ppm from?

    the current CO2 level is already at its lowest using an electric regulator, any lower and i will have problem regulating it...

    yes, my office aircon goes off at night... but maybe the high temperature could be because i was putting the lights within 1 inch of the water surface before? i am putting them 3 inches away now...

  16. #16
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    Maybe you can do some reading at http://www.csd.net/~cgadd/aqua/art_plant_co2chart.htm
    Hope this clears up your CO2 level doubts...and yes the when air-con if "off" the change in temperature of the tank water could cause much harm to your fish and shrimps. Maybe you can invest in a thermometer to check the temperature of your tank when aircon is "on" and temperature in the morning when aircon is still "off"?
    Plant Physiology by Taiz and Zeiger

  17. #17
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    ----------------
    the change in temperature of the tank water could cause much harm to your fish and shrimps.
    ----------------
    Peter,

    could you explain where you are coming from with your comment? i.e. in what way would a change of temperature cause much harm?

    Irn-bru,

    One simple way to check if your CO2 levels are ok is to switch off your CO2 injection for a day, and then measure your PH level (in other words, your ph with just ambient co2 dissolved). After that, simply switch on your injection and target for a 0.6 drop in your ph... that will typically give you approx 15ppm co2 dissolved.
    Allen

  18. #18
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    Allen, Irn-Bru mention that the aircon is "off" during the night which would cause the temperature of the tank to rise even if the lightings are "off" (suppose the tank temperature with air-con is 22-25 degrees and once the aircon is "off"..temperature would slowly creep up to normal ambient temperature. This constant change of temperature would affect the creatures in the tank.)

    Regarding your point that drop in 0.6 of pH reading would give you a CO2 level of 15ppm...I beg to differ though. Example with no CO2 injection my pH is 8 and KH is say 3 which will give me 0.9ppm of CO2. With your theory that drop in 0.6 of pH will give you 15ppm? (pH 7.4 and KH 3 = 3.5ppm of CO2 only?)
    Plant Physiology by Taiz and Zeiger

  19. #19
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    Oh I see what you mean about the temperature... yes the varying temperature could be unsettling for the fish as stability of the environment is always nice... How much it actually affects the fish I'm not sure. But I see your point.

    As for my drop of 0.6ph being wrong, I think I need to explain. You calculated again your co2 level basing upon the calculator. and yes based on the calculator a PH of 8 and KH of 3 will imply a CO2 level of 0.9ppm. The one mistake I did make is that it is 0.5 drop and not 0.6. a drop of 0.6 in ph will give you a higher level of roughly 19ppm.

    Now I'm basing my assumption on this... the level of CO2 dissolved in water at ambient conditions, is 5ppm. Ignore PH ignore KH... not 0.9ppm (This is where the basic assumptions of the calculator again can introduce problems). Now if we look at the charts for CO2/PH/KH (which are based on the same formula as the calculator), you will see that regardless of your KH, a drop of 0.5ph from your ph level at ambient conditions will result in a CO2 level of roughly 15-16ppm. The only difference is that this method doesn't try to assume your starting point... you can go to this link for some CO2 charts

    http://www.thekrib.com/Plants/CO2/kh-ph-co2-chart.html

    For example, my initial kh is 4 and ph is 7.4 my CO2 is 5ppm. If I drop my ph to 6.9, my CO2 goes to 15ppm.

    If you juggle about the formula used, you will find that for a PH of X and a KH of Y that gives a CO2 level of 5ppm, then a PH of X-0.5 and KH of Y will always give CO2 of roughly 15ppm (roughly).

    The first time I read about this I was really puzzled... could the mystery of good CO2 injection be as simple as a 0.5-0.6PH drop? surely not... then again the writer was the well known karen randell (if memory serves me). so I did some playing around, and basically it looks right.

    Having said all this, I'm no expert in mathematics or science... perhaps my own assumptions are wrong... if such is the case, then so be it... live and learn!
    Allen

  20. #20
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    sigh, another one bites the dust...
    i am all clear of Malayan shrimps now...
    wonder will my cherry shrimps be next...

    allen, will stopping my CO2 injection for a full day kill my plants?

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